Dreams can be entertaining, disturbing, or downright bizarre. We all dream -- even if we don't remember it the next day. But why do we dream? And what do dreams mean, anyway?

WebMD takes a look at what makes us dream and helps unravel the mysteries behind dreams.

What Are Dreams?

Dreams are basically stories and images our mind creates while we sleep. Dreams can be vivid. They can make you feel happy, sad, or scared. And they may seem confusing or perfectly rational.

Dreams can occur anytime during sleep. But most vivid dreams occur during deep, REM (rapid eye movement) sleep, when the brain is most active. Some experts say we dream at least four to six times per night.

Why Do We Dream?

There are many theories about why we dream, but no one knows for sure. Some researchers say dreams have no purpose or meaning and are nonsensical activities of the sleeping brain. Others say dreams are necessary for mental, emotional, and physical health.

Studies have shown the importance of dreams to our health and well-being. In one study, researchers woke subjects just as they were drifting off into REM sleep. They found that those who were not allowed to dream experienced:

If you go to bed with a troubling thought, you may wake with a solution, or at least feel better about the situation.

Sigmund Freud believed dreams are a window into our subconscious. He believed they reveal a person's:

Unconscious desires

Thoughts

Motivations

Freud thought dreams were a way for people to satisfy urges and desires that were unacceptable to society.

Perhaps there is merit with all these theories. Some dreams may help our brains process our thoughts and the events of the day. Others may just be the result of normal brain activity and mean very little, if anything. Researchers are still trying to figure out exactly why we dream.

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What Do Dreams Mean?

Just as there are varying opinions as to why we dream, there are also different views as to what dreams mean. Some experts say dreams have no connection to our real emotions or thoughts. They are just strange stories that don't relate to normal life.

Others say our dreams may reflect our own underlying thoughts and feelings -- our deepest desires, fears, and concerns, especially recurring dreams. By interpreting our dreams, we may be able to gain insight into our lives and ourselves. Many people say they have come up with their best ideas while dreaming, so dreams may be a conduit of creativity.

Often people report having similar dreams -- they are being chased, fall off a cliff, or appear in public naked. These types of dreams are likely caused by a hidden stress or anxiety. While the dreams may be similar, experts say the meaning behind the dream is unique to each person.

Therefore, many experts say not to rely on books or "dream dictionaries," which give a specific meaning for a specific dream image or symbol. The particular reason behind your dream is unique to you.

Although scientists can't say for sure what dreams mean and why we dream, many people find meaning in their dreams.

Why Do Nightmares Occur?

Nightmares, or bad dreams, are common in children and adults. Often nightmares are caused by:

If you have a recurring nightmare, your subconscious may be trying to tell you something. Listen to it. If you can't figure out why you are having bad dreams, and you continue to have them, talk to a qualified mental health care provider. They may be able to help you figure out what is causing your nightmares and provide tips to put you at ease.

Keep in mind that no matter how scary a nightmare is, it is not real and most likely will not happen to you in real life.

What Are Lucid Dreams?

Have you ever had a dream where you knew you were dreaming during your dream? This is called a lucid dream. Research has shown that lucid dreaming is accompanied by an increased activation of parts of the brain that are normally suppressed during sleep. Lucid dreaming represents a brain state between REM sleep and being awake.

Some people who are lucid dreamers are able to influence the direction of their dream, changing the story so to speak. While this may be a good tactic to take, especially during a nightmare, many dream experts say it is better to let your dreams occur naturally.

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Can Dreams Predict the Future?

There are many examples of situations where a dream came true or was telling of a future event. When you have a dream that then plays out in real life, experts say it is most likely due to:

Coincidence

Faulty memory

An unconscious tying together of known information

However, sometimes dreams can motivate you to act a certain way, thus changing the future.

Why Are Dreams Hard to Remember?

Researchers don't know for sure why dreams are easily forgotten. Maybe we are designed to forget our dreams because if we remembered all our dreams, we might not be able to distinguish dreams from real memories.

Also, it may be harder to remember dreams because during REM sleep our body may shut down systems in our brain responsible for creating memories. We may only remember dreams that occur just before we wake, when certain brain activities have been turned back on.

Some say our minds don't actually forget dreams, we just don't know how to access them. Dreams may be stored in our memory, waiting to be recalled. This notion may explain why you may suddenly remember a dream later in the day -- something may have happened to trigger the memory.

Tips for Dream Recall

If you are a sound sleeper and don't wake up until the morning, you are less likely to remember your dreams compared to people who wake up several times in the night. But here are some tips that may influence your ability to remember your dreams:

Wake up without an alarm. You are more likely to remember your dreams if you wake up naturally than with an alarm. Once the alarm goes off, your brain focuses on the annoying sound and turning it off and not your dream.

Remind yourself to remember. If you want to remember your dreams and make a conscious decision to do so, you are more likely to remember your dreams in the morning. Before you go to sleep, remind yourself that you want to remember your dream.

Dream playback. If you think about the dream right after waking, it may be easier to remember it later.

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How to Make Sense of Your Dreams

If you are intrigued by your dreams or want to sort out the meaning behind them, consider keeping a dream diary or journal. Here are some tips:

Write it down. Keep a notebook or journal and pen next to your bed and record your dream first thing every morning, while the memory is still fresh. Write down anything you recall from the dream and how it made you feel, even if you can only remember random pieces of information.

Journal without judgment. Dreams are sometimes odd and may go against societal norms. Try not to judge yourself based on your dreams.

Give each dream a title. This may help if you want to refer back to a dream. Sometimes the title you create can provide insight on why you had the dream or the meaning behind it.

Dreams have fascinated humanity since the beginning of time and will likely continue to mystify us. And although science has allowed us to learn much about the human brain, we may never know for sure the meaning behind our dreams.